Food products and other perishable items are often packaged using tubular containers which are sealed at both ends. The tubular containers typically include at least one structural body ply, which is advantageously formed of paperboard, a liner ply on the inner surface of the body ply to provide an impervious barrier to liquids, moisture and some or all gasses, and a label ply around the outside of the body ply for designating the product packaged therein. End closures are applied on both ends to enclose the container.
At least one of the ends is preferably provided with a release strip which allows quick and easy opening of the tubular container by the consumer. These release strips may take several forms, although a common configuration is a release strip which is wrapped around one end of the tubular container before the respective end closure is applied. The end closure is then placed over the end adjacent to the release strip and a generally radially projecting flange of the closure is bent towards the outer surface of the tubular container so as to engage firmly the release strip between the outer surface of the tubular container and the flange. A tab portion is typically provided at one end of the release strip so that a consumer can pull the tab portion and the release strip will be disengaged from between the flange of the end closure and the outer surface of the tubular container. Accordingly, a clearance will be provided between the end closure and the tubular container, and the end closure can then easily be removed.
A typical apparatus for securing release strips to tubular container bodies is disclosed in U.S. Pat. No. 3,690,997 to Bofinger, et al. A roll of plastic web material for the strips is unwound and fed to a cutting member which forms the individual strips. The strips are then advanced in a direction perpendicular to the feed direction of the plastic web material to a vacuum wheel where one entire surface of the strip (having a substantially constant width) is engaged against the peripheral surface of the vacuum wheel. An adhesive is applied to the opposite surface of the release strip by an adhesive roll. An applicator turret rotates the tubular containers against the release strip surface to adhere the release strips to the tubular containers. The adhesive applicator roll is provided with a narrow annular peripheral extension which applies a single adhesive band along the full longitudinal length of the strip including the tab in an area which is disposed adjacent that edge of the strip which is to be farthest removed from the adjacent edge of the tubular body to which the strip will be applied.
In one embodiment, the tab is provided with a circular hole which, when adhered to the container, overlies the opposite end of the release strip. A similar release strip configuration is illustrated in U.S. Des. Pat. No. 208,222 to Slomski. One disadvantage of these container types, however, is that the tab portion provides a limited area for allowing the consumer to initiate and continue removal of the release strip. It is possible for the tab to slip from the grasp of the consumer when pulling on the tab portion. In addition, it has been determined that it is easier to open containers if the tab portion can be twisted relative to the remainder of the release strip during removal thereof. However, the release strips of the prior art have a substantially constant width in the circumferential direction making twisting of the tab portion during removal difficult.
An alternative configuration is disclosed in U.S. Pat. No. 3,409,200 to Balocca et al, wherein a release strip is provided having a slightly enlarged pull tab extending in a direction away from the end closure. An adhesive for adhering the elongate portion of the release strip may be extended to cover the tab and adhere the tab to the container body. This tab configuration may also not provide a sufficiently graspable area to allow the release strip to be easily removed and the tab of this design can also slip from the grasp of the consumer.
If the size of the tab is increased to facilitate better grasping, additional adhesive is required to adhere the enlarged tab to the tubular container, thus adding to the expense of the container. Conversely, if the end portion of an enlarged tab is not adhered to the container, the free end of the tab can become accidentally snagged during the manufacture or subsequent handling of the container such that part of the release strip may be prematurely removed.
One attempt to solve the problem of outwardly extending tabs during handling is disclosed in U.S. Pat. No. 3,330,436 to Slomski. An adhesive bond is provided between the inside surface of the tab and the subjacent tubular container surface and is in alignment with the adhesive band on the elongate portion of the release strip. However, the container of this patent also suffers from having a small tab which can be difficult to grasp. Accordingly, there is a need for a release strip having an easily engaged tab which facilitates removal and eliminates or greatly reduces slipping of the tab from the grasp of the consumer. Such a release strip preferably would not extend outwardly so as to damage or cause partial premature removal of the release strip during handling of the container.